1. Field of the Invention
This invention relates to a process for improving the yield of acid cheese cure in cheesemaking.
2. Description of the Prior Art
U.S. Pat. No. 3,039,879 -- Vakaleris, describes a process for increasing the yield of solids from milk during cottage cheese manufacture by retaining additional protein in the curd. Milk is heat treated at high temperatures between 127.degree. C. to about 149.degree. C. for short periods of time to denature the milk protein and immediately cooled. Between 40 and 80% of the protein is denatured. Denaturation in excess of 80% of the protein results in browning, cooked flavor and adverse conditioning of the protein so care must be taken during heat treating. The cooled, heat treated milk is converted into cottage cheese curd by setting the milk with lactic acid starter and rennin and then cutting the curd.
The prior art also describes various processes for recovery of soluble protein from milk whey. U.S. Pat. No. 2,377,624 -- Gordon, issued Apr. 5, 1945, discloses a process which involves acidifying milk whey to a pH of 1.0 to 4.3 and then adding condensed phosphates to precipitate the protein from the whey. This process has several disadvantages. For example, specific gravity of the precipitated protein is not sufficiently high to permit its separation from the water phase using commercially available equipment. Protein separation is also complicated by its low concentration, i.e., about 0.5 to 0.6 parts by weight of soluble protein per 100 parts by weight of whey.
Canadian Pat. No. 790,580 -- Wingerd, issued July 23, 1968 describes a milk protein phosphate reaction product obtained by acidifying whey, then denaturing the protein in the acidified whey by heat treating, thereafter adding a solution of potassium polyphosphate and a sodium salt solubilizer to precipitate the denatured protein from the whey and separating the precipitated protein reaction product by centrifuging or filtering.
U.S. Pat. No. 3,864,506 -- Grindstaff et al., issued Feb. 4, 1975 describes treatment of cheese whey with a condensed phosphate at a pH of 5.5 to 4.0, then adjusting the pH to 6.5 to 8.0 with base to precipitate the protein and separating the precipitated protein from whey by filtration.
It will be noted that none of the above processes using condensed phosphate is concerned with precipitation of protein in the curd during cheesemaking but in the separation of protein from milk whey after the whey has been separated from the curd.